1. Field
The present application relates generally to the transmission of information over a distribution network, and more particularly, to methods and apparatus for time tracking using assistance from TDM pilots in a communication network.
2. Background
Data networks, such as wireless communication networks, have to trade off between services customized for a single terminal and services provided to a large number of terminals. For example, the distribution of multimedia content to a large number of resource limited portable devices (subscribers) is a complicated problem. Therefore, it is very important for network administrators, content retailers, and service providers to have a way to distribute content and/or other network services in a fast and efficient manner and in such a way as to increase bandwidth utilization and power efficiency.
In current content delivery/media distribution systems, wide area and local area real-time and non real-time services are packed into a transmission frame and delivered to devices on a network. For example, a communication network may utilize Orthogonal Frequency Division Multiplexing (OFDM) to provide communications between a network server and one or more mobile devices. Using this technology a transmission frame can be generated that has data slots packed with services to be delivered over a distribution network as a transmitted waveform.
Typically, a transmitter operates to transmit the transmission frames over a transmission channel to devices in communication with the network. Unfortunately, it is possible that the transmission channel will experience conditions that will make it difficult for receiving devices to recover the transmitted data. For example, it is possible that channel delay spreads will become very long or that channel conditions, which define the channel profile, will change rather quickly. In both instances, the result may be inaccurate OFDM symbol timing at the receiver that prevents the receiver from accurately decoding the transmitted data.
Therefore, it would be desirable to have a system that operates to provide accurate time tracking thereby avoiding the problems associated with long delay spreads and fast changing channel conditions.